Mura has the ability to create different display regions for users to add content from within the site manager. For example, if a user wanted to add a sub navigation to a folder, they would select the Sub Navigation object and add that to the "Left" Display Region on the page.
By default, Mura has three display regions configured for the Left Sidebar, Main Content, and Right Sidebar.
To create additional display regions:
The display regions you create will now appear on the Layout & Objects tab when you edit content in the Site Manager.
You can then add content objects to each of the available display regions. To add a Sub Navigation for example:
To utilize display regions within your templates, you need to refer to the ID of the display region and dynamically place it within the proper context of your templates. For example, if you assigned Display Region #1 as the Left Column display region, you would first account for what the left column should look like in your markup (i.e. three columns if you're using a CSS grid framework), then you can place the following code with the markup:
<aside class="sidebar left"> #$.dspObjects(1)# </aside>
This will tell Mura that any time a user places an object to the "Left" display region, it will render within this markup.
Also see Mura CMS Documentation: Site Settings (including display region settings)